| 摘要 |
PURPOSE:To prevent the fracture at the sealing section by sealing a niobium tube or a tantalum tube directly to the inner face at the end of a linear single crystal alumina light emitting tube. CONSTITUTION:A niobium tube or a tantalum tube 4, 5 provided with the electrodes 6, 7 are directly sealed through a ceramic cement to both chip sections of a light emission tube 1 made of single crystal alumina. Furthermore in order to increase the temperature at the coolest point in the tube, thermal protective films 10, 11 are provided at both end sections of the light emission tube 1. Consequently the fracture of the light emission tube at the sealing section can be protected, resulting in a high pressure sodium lamp having improved efficiency under heavy load lighting. |
